Self-cleaning Spiro-OMeTAD via multimetal doping for perovskite photovoltaics
Sisi Wang, Shaochen Zhang, Xiaohuo Shi, Canglang Yao, Donger Jin, Danyu Gu, Yinjuan Chen, Jiazhe Xu, Jingjing Xue, Rui Wang
Abstract
Record power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) are usually achieved using organic spiro-OMeTAD. However, conventional doping with hygroscopic dopants (LiTFSI and tBP) leads to compromised device stability. We introduce a synergistic mixed doping strategy that utilizes a combination of metal-TFSI dopants—LiTFSI, KTFSI, NaTFSI, Ca(TFSI)2, and Mg(TFSI)2—to enhance doping efficiency while effectively removing hygroscopic contaminants from the Spiro-OMeTAD solution. This approach achieves PCEs exceeding 25% and significantly improves stability under harsh environmental conditions. Notably, Ca(TFSI)2 and Mg(TFSI)2 facilitate enhanced oxidative doping, while NaTFSI promotes interstitial doping in the bulk perovskite. Additionally, KTFSI serves as a catalytic agent, lowering the reaction energy barrier for the other dopants, thereby accelerating spiro-OMeTAD ion radical production. These findings underscore the potential of synergistic doping in optimizing the performance and longevity of photovoltaic devices. Conventional doping with hygroscopic dopants could lead to compromised device stability in perovskite solar cells. Here, the authors employ a combination of metal salt dopants to enhance doping efficiency and remove hygroscopic contaminants, realizing efficiency of over 25% for stable devices.